U.S. Pat. No. 4,997,096 discloses a child-resistant closure having inner and outer plastic shells. The outer plastic shell has a base wall, a peripheral skirt and a circumferential array of lugs on an undersurface of the base wall. The inner plastic shell has a base wall, a peripheral skirt, at least one internal thread segment on the skirt, and a circumferential array of lugs on an outer surface of the base wall for opposed engagement by the internal lugs on the base wall of the outer shell. To remove the closure when it is threaded onto a container neck finish, the outer shell must be pushed axially against the inner shell and simultaneously rotated so that the lugs on the outer shell engage the lugs on the inner shell and rotate the inner shell with respect to the container neck finish. When the outer shell is rotated without applying an axial force to the outer shell, the lugs on the outer shell simply cam over the lugs on the inner shell and do not rotate the inner shell with respect to the container neck finish. Child-resistant closures of this type have been marketed for many years by applicants' assignee under the trademark ARGUS-LOC. See also GB 1529999. A general object of the present disclosure is to provide improvements in child-resistant closures of this type, and to provide packages that include such improved closures.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A plastic shell for a two-piece push-and-turn child-resistant closure in accordance with one aspect of the present disclosure includes a peripheral skirt, and a base wall from which the peripheral skirt depends. The base wall has a peripheral portion having a first thickness, a plurality of lugs disposed at least in part on the peripheral portion adjacent to the peripheral skirt, and a central portion having a second thickness less than the first thickness. The central portion includes a plurality of ribs having a third thickness greater than the second thickness and substantially equal to the first thickness and extending from the first peripheral portion toward a center of the base wall.
A child-resistant closure in accordance with another aspect of the present disclosure includes a plastic outer shell having an outer base wall with an outer peripheral portion and an outer central portion disposed within the outer peripheral portion. The outer shell also has an outer peripheral skirt extending from the outer peripheral portion, and a plurality of internal lugs disposed at least in part on the outer peripheral portion. A plastic inner shell of the closure has an inner base wall with an inner peripheral portion and an inner central portion disposed within the inner peripheral portion. The inner shell also has an inner peripheral skirt extending from the inner peripheral portion, at least one internal thread segment on the inner peripheral skirt, and a plurality of external lugs disposed at least in part on the inner peripheral portion of the inner base wall adjacent to the inner peripheral skirt for engaging the internal lugs of the outer shell. At least one of the central portions of the base walls has an array of ribs substantially equal in thickness to its corresponding peripheral portion.
A child-resistant closure in accordance with a further aspect of the disclosure includes a plastic outer shell including an outer peripheral skirt, and an outer base wall from which the outer peripheral skirt depends and having a plurality of internal lugs adjacent to the outer peripheral skirt. A plastic inner shell of the closure is disposed within the outer shell and includes an inner peripheral skirt with at least one internal thread segment, and an inner base wall from which the inner peripheral skirt depends and having a plurality of external lugs adjacent to the inner peripheral skirt. The outer base wall of the outer shell has an outer peripheral portion of a first thickness on which the internal lugs are disposed, an outer central portion having a second thickness less than the first thickness and including an outer plurality of ribs having a third thickness greater than the second thickness and substantially equal to the first thickness and extending in a direction from the outer peripheral portion toward an outer center of the outer base wall. The inner base wall of the inner shell has an inner peripheral portion of a fourth thickness on which the external lugs are disposed, an inner central portion having a fifth thickness less than the fourth thickness and including an inner plurality of ribs having a sixth thickness greater than the fifth thickness and substantially equal to the fourth thickness and extending in a direction from the inner peripheral portion toward an inner center of the inner base wall.